In the past, applications and services for transferring image data (in particular, motion picture data) via various kinds of networks such as the Internet and LAN (Local Area Network) are widely used. When image data are transmitted and received via a network, in many cases, the amount of data is reduced by encoding (compression) processing at the transmission side and the reduced data are transmitted to the network, and then the reception side performs decoding (extraction) processing on the encoded reception data to reproduce the data (for example, see Patent Document 1 to Patent Document 6).
In some cases, the transmission of motion picture data requires timeliness (so-called real-time property). For example, when an image captured and obtained by an image-capturing device at a transmission source is displayed immediately (in so-called real-time manner) on an image display apparatus at a transmission destination, displaying of a motion picture may be corrupted if there is too much delay in encoding, transmission, decoding, and the like of image data. In such case, in order to ensure displaying of motion picture, it is required to manage the delay time in transmission of image data (including processing related to transmission such as encoding and decoding).